| 摘要 |
<p>PURPOSE:To accurately detect input voltage without irregularity, by connecting the third resistor to the terminal of the first resistor and that of a light emitting part of an optical coupling element. CONSTITUTION:When voltage VR to be detected approaches the reference voltage built in a shunt regulator 1 and the internal circuit of the regulator 1 starts operation, a current begins to flow to the third resistor 8. Since the resistance value of the third resistor 8 is lower than that of the first resistor 3, no current flows to the light emitting part 2a of an optical coupling element through the resistor 3 and the voltage drop generated between both terminals of series connection of the resistor 3 and the light emitting part 2a becomes a small value. At the point of time when the voltage VR becomes equal to the reference voltage, the unit of the output terminal K of the regulator 1 lowers from the voltage V1 of the first DC power source 5 to the voltage VK and voltage (V1-VK) is applied to the resistor 3 and the light emitting part 2a. Therefore, the light emitting part 2a is saturated and a current flows through the resistor 3. By this method, the imperfect non-linear characteristic in the output characteristic of the regulator 1 is corrected and accurate voltage VR can be detected.</p> |
